FYI:

When I replace arch/powerpc/sysdev/ppc4xx_msi.c from a 3.6 kernel with a
ppc4xx_msi.c from 47da421981571c69ef29740cc55fa7248682e167 it boots from
nfs with a defconfig, so this seems to be the guilty one.

Please find attached the difference between the good and bad
ppc4xx_msi.c files.

I'll be happy to test your patches;)

Regards,

Robert